1. Field Of The Invention
The invention relates generally to suspension components on vehicles, and more particularly to a shock absorber with a damper valve that incorporates a blocker with a variable profile and a bias to provide adjustable damping of suspension compression.
2. Description Of The Related Art
Conventional shock absorbers employ a piston in a cylinder containing a substantially incompressible fluid. Orifices in the piston and passages leading to a fluid reservoir regulate the flow of the fluid so as to damp the oscillation of a suspension spring. In more advanced designs, a damper valve may also be incorporated at an end of a suspension or shock absorber. Valves of this design open progressively with greater force and can be used to damp low-speed compression and/or extension of shock absorbers while preventing pressure “spikes” and consequent harshness of ride when the suspension must compress deeply and quickly. They can also permit the shock to extend rapidly after deep compression while slowing it sufficiently near maximum extension to prevent harsh “topping out”.
A traditional front fork is shown in FIGS. 1 and 2, FIG. 2 being a section of one leg of the fork. A damper may be conventionally incorporated into the area shown in dashed lines on FIG. 2.
A damper currently in production by Mountain Racing Products is shown in FIGS. 3 and 4, FIG. 3 being an exploded view of FIG. 4. In this prior art embodiment of a damper 300, a blocker 302 is used to variably block apertures 304 in a housing 306. The blocker 302 is biased towards a ramped portion 312 using a spring 308 and a magnet 310. Teeth 314 project from a bottom end 316 of the blocker 302. When the blocker 302 is rotated by an external adjuster (not shown), each tooth 314 rides along a sloped guide 318 in the ramped portion 312. This rotational movement rotates the blocker 302 relative to the housing 306 and the apertures 304. In addition, the rotational movement also axially moves the blocker 302 relative to the housing 306. This axial position of the blocker 302 governs the amount of the apertures 304 that are exposed and through which fluid can flow without triggering the valve. FIG. 4 shows the blocker 302 in a high axial position, exposing almost all of each aperture 304. Upon application of a force on the bottom end 316 of the blocker 302 due to a compression stroke, the blocker 302 moves axially to most fully expose each aperture 304 and maximally allow fluid to flow through the apertures 304.
However, in such a design, the amount of force required to begin the opening of the valve will vary, depending on the rotational position of the blocker. This is because adjusting the rotational position of the blocker will also adjust the axial position of the blocker. This change in axial position will also change the preload on the spring and will move the magnet to reduce the magnetic closing force.
Accordingly, it may be desirable for a damper to allow for an adjustment of the valve to allow variable damping, while having a consistent force profile for fluid overcoming the bias and opening the valve to a completely open position and reclosing the valve. Further, it may be desirable for such a design to have a reduced turbulence and viscous drag to improve fluid flow through the aperture.